Independent jig grinder



23, 1955 A. s. HANCOCK, JR 2,715,806

INDEPENDENT JIG GRINDER Filed May 23, 1952 33 INVENTOR. c fi/berf 5 f/ancacIJn BY HTTORNEY United States Patent INDEPENDENT 31G GRINDER Aihert 3. Hancock, Jr., Orange City, Iowa Application May 23, 1952, Serial No. 289,627

3 Claims. (Cl. 51261) My invention relates to a jig grinder.

An object of my invention is to provide a grinding tool which is in the form of a small, lightweight, selfcontained unit which can be placed in the collet or drill chuck of a milling machine, jig borer, drill press, or similar machine and which is used to grind holes to accurate dimensions from a pre-selected minimum to maximum diameter.

A further object of my invention is to provide means wherein the grinding spindle and grinder head are rotated by a common power source such as the drill press, etc., and wherein the grinding head will rotate to provide the circular path of rotation required during the grinding action and with further means controlled by certain centrifugally operated means.

With these and other objects in view, my invention consists in the construction, arrangement, and combination of the various parts of my device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawings, in which:

Figure l is a sectional view of the unit taken generally along the lines 11 of Figure 6,

Figure 2 is a sectional view taken generally along the lines 22 of Figure 1,

Figure 3 is a sectional view taken generally along the lines 3-3 of Figure 1,

Figure 4 is a schematic view of the grinding wheel showing the use thereof for various sized openings or holes,

Figure 5 is a detail,

Figure 6 is a reduced size plan view of the unit taken generally along the lines 6-6 of Figure l, and

Figure 7 is a sectional detail view showing the coaction of plate 18 with slots 20.

My invention contemplates the provision of a grinding tool for grinding holes to accurate dimensions, etc, and wherein the grinding tool will not require separate power sources other than the original power source, for rotating the tool about a vertical axis for peripherally grinding the hole, my invention also contemplating certain adjustable arrangements included therein for effecting correct diameters of the holes to be ground or finished, as well as means for regulating the speed of rotation of the entire unit.

I have used the character 10 to designate a vertically positioned shaft which is adapted to be tightly secured by means of the chuck 11 of a drill press for instance, it being understood however that the shaft 10 can be attached to any other source of power.

The shaft 10 is journalled within the bearings 12 which are afiixed to the cylindrical member 13 which is a portion of the grinder body assembly, the shaft 10 being suitably attached to a larger pulley 14, and engaging the pulley 14 is a belt 15 which engages a further smaller pulley 16.

The pulley 16 is attached to a shaft 17 which passes through a supporting carriage 18, the carriage 18 having side portions at 19 (see Figure 3) which slide in suitable slots 20 provided in the side walls 21 of an enclosing casing having an upper wall 22 and end walls 23.

The shaft 17 is attached to a further pulley 24 which is mounted beneath the carriage 18, the pulley 24 being the same diameter as the pulley l4. Engaging the pulley 24 is a further belt 25 which passes over the further smaller pulley 26, the pully 26 being of the same size as the pulley 16, the pulley 26 aslo normally having its axis directly in alignment with the axis of the shaft 10, except when the various diameter holes are to be ground.

The pulley 26 is attached to a shaft 27 which is journalled within the bearings 28, the shaft 27 being secured to the spindle 29. Secured to the shaft 27 is a clamping chuck or head 30 in which the shaft 31 is attached, the shaft 31 being attached to the usual type of small grinding wheel 32, the character 33 indicating the opening or hole to be ground in the member 34 which is suitably attached to the base plate 35.

The bearings 28 are secured within the tapered boss 36, the boss 36 being an integral continuation of the plate 37, which plate 37 is pivotally mounted at 38 on the pin 39 which terminates in the head 40, the pin 39 being suitably secured as at 41 to a plate 42 which is secured at 43 to the casing walls 21 and 23. The plate 37 continues into the outer portion 44 which includes an arcuate slot 45, and passing through the plate portion 44 is a threaded stud 46 which is threadably engaged within the boss 47 which extends from one of the walls 23, the stud 46 terminating in the knurled binder screw 48.

Pivotally engaged at 49 with the plate portion 44 is a circular member 51) having a transverse slot 51 therein in which slot is fitted the tongue 52 which tongue extends from a traverse nut 53 which nut is threadably engaged with the traverse screw 54, the screw 54 being suitably journalled at 55 and 56 and being suitably retained against longitudinal movement thereat. The traverse screw 54 terminates at the knurled knob 57 which can include suitable markings along the flange portion 58 adapted to register with other markings on the casing at 59 for indicating the proper diameter of the opening to be ground. Attached at the end of the carriage 18 is the flange 60, through which passes a pin 61 to which is attached the cotter key 62, the pin 61 terminating at the expanded end 63, and positioned between the portion 63 and the flange 66 is the helical compression spring 64.

Securely attached to the portion 13 is a ring gear 65, and receiving the portion 13 is a journalling member 66 which is secured to a collar 67 which provides a portion of the governing mechanism, the bearing 66 being secured by means of the slotted nut 68 threadably engaged with the member 13.

Engaging the gear is a further gear 69 which is attached to a shaft 76 which is suitable journalled within the governor casing 71. The gear 69 meshes with a further gear 72 which is secured to a further shaft 73 which is suitably journalled, and attached to the shaft 73 is a further larger gear 74 which meshes with a still further smaller gear '75 which is secured to a vertical shaft 76 which is suitably journalled as shown within the member 71.

Extending upwardly from the casing 71 is a governor housing portion 77 with which is threadably engaged at 78 a cap 79 having an opening 80, the upper end of the shaft 76 being received within the opening 80, this upper end being journalled at 81, and attached to the shaft 76 is a collar 82 adapted to bear aaginst a helical spring 83, which spring 83 receives the shaft 76, the lower end of the spring 83 bearing against the cars 84,

which ears are attached to the governor arms 85 which arms 85 terminate in the upper weighted portions 86, the ears 84'being pivoted at 87 to the collar 88 which is attachedto the shaft 76. Secured to the arms 85 are the small friction pads 83a, for applying a varying friction against the housing 77.

Extending from the casing portion 71 is a portion 89 having the openings 90 and 91 therein, and threadably engaged at 92 with the portion 89 is a machine screw 93. Bolted to the side portions 19 of the carriage 18 which project through the slots 20 provided in the side walls 21 of the enclosing casing are the plates 94 which limit the end play of the carriage in the casing and insure accurate longitudinal movement of the carriage or pulley assembly member 18. If belts not requiring tension adjustment, such as the Gihner timing belts, are used for belts 15 and 25, longitudinal movement of the carriage 18 in the casing is not required and the carriage 18 may be fastened inl'no'vably to the casing side walls 21.

It should be understood throughout the description herein, that although the bearings are shown in the form of conventional bronze bearings or the like, roller bearings or ball bearings can be employed if desired, especially in the case of the shaft 27 for instance.

When the device is set up for operation, it will appear substantially as shown in Figure 1, the operation and use of the unit being as follows. It will be noted that the shaft 27 which carries the grinding wheel 32; at its minimum position is directly beneath, and in alignment with the shaft 10. For adjusting the body so that the small grinding wheel 32 will travel in an annular path about the circular surface to be ground, the knob 57 is rotated so that the threaded engagement of the stud 54 with the traverse nut 53 will cause the tongue 52 which engages within the member 50 to carry the plate 37 in the direction of the arrow 95 (see Figure 2) so that the grinding wheel 32 will then be off-center with respect to the vertical axis of the shaft 10, so that when the entire casing 21, 22 etc. rotates, this grinding wheel will correspondingly travel in a circular path substantially as indicated by the arrows 96 in Figure 4, such figure showing the path of travel with respect to different size openings. Figure 3 also illustrates the adjustment wherein the shaft 27 and pulley 26 are carried in an arc to the selected position. In this manner any size of opening within the limits of the unit can be preselected for the grinding operation, the knurled binder screw 48 and stud 46 or a suitable head binder screw, providing tightening means after the adjustment is made, it being noted also that the member 50 can pivot corresponding'to the different angular positioning of the stud 54 with respect to the traverse nut 53. It will be noted that the shaft 10 by virtue of the pulley and further shaft arrangements will drive the shaft 27 at a considerably increased rate of speed, and it will be further noted that the spring tension of the spring 64 will maintain tension on the belts at all times, the mounting of the pulleys also being always correctly in line due to the fact that the pivoting of the plate 37 on the pin 39 is directly in substantial vertical alignment with the centers of the pulleys 16 and 24. The slot 45 permits a relatively wide range of adjustment for the correct diameter of the hole to be ground.

It will now be obvious that, due to the friction of the various bearings and shafts within the casing 21, 22 etc., this entire casing will rotate in the same direction of rotation of the shaft 10, and in a circular path about the shaft 10 after the adjustment is made for diameter by virtue of the knob 57 and the indexing thereon. If the grinder wheel 32 is placed in contact with the work piece opening 33, the added resistance will tend to make the grinder unit or casing rotate faster than the speed of the shaft 10, and by virtue of this resistance of the bearings etc. it will be noted that a path of rotation is provided in the direction of the spindle rotation of the member 10, and if heavier cuts are taken with the grinder,

greater force is applied against this resistance to maintain rotary motion of the entire casing unit. At no time is the rotary force torque on the unit greater than the resistance of the bearings plus the resistance of the grinding wheel against the work. The governor mechanism and the gears provide the result of controlling this torque to maintain a constant speed of rotation of the grinding wheel through the application of a small resistance between a stationary part of the machine upon which the grinder is mounted and the grinder body. This is accomplished through the use of the governor assembly etc. as stated, and in the following manner.

It will be noted that the grinder unit or casing is free to rotate within the bearing 66, and a rod 97 is inserted within the opening 90 and tightened by means of the machine screw 93, the rod then bearing against any stationary portion of the machine to prevent rotation of the governor body and housing. The gear 65 meshes with the smaller gear 69 which meshes with the train of further gears as shown, driving the shaft 76. It will be noted that as the grinder body rotates inside of the stationary governor assembly unit, that the small shaft 76 will rotate at a considerably greater speed than the casing. Assuming, by the ratios involved, that the shaft 76 rotates ten times as fast as the grinder body, if a resistance were applied to the shaft 76, of one-tenth of the torque rotating the grinder body or casing, rotation would cease. The resistance required is small and is provided by means of the governor member above described.v For instance as the speed approaches the desired amount, the centrifugal force will throw the clutch pads 88 in contact with the governor body portions 77 thereby stopping further acceleration. If the cap 79 is screwed downwardly the spring 83 is compressed against the centrifugal force by virtue of the ears 84, allowing the counterweights 86 to rotate faster before they move the clutch pads 88a in contact. By virtue of this arrangement the speed of retation of the grinder body can be selected, by turning the cap 79 on the governor assembly while the body is rotating, and it will be noted that it will maintain a constant speed regardless of spindle speeds or wheel load. In some cases, the opening 91 can be employed with the rod 97, and for the same purpose.

It will now be noted that this grinder unit will provide a variety of functions in a single unit without requiring extra power sources and will also provide all of the advantages mentioned in the objects of my invention, with other advantages being readily apparent.

Some changes may be made in the construction and a1" rangement of the parts of my invention without depart- T which said further shaft is journalled, a third larger pulley attached to said further shaft, a fourth smaller pulley driven by said third pulley, a grinding shaft atached to said fourth pulley including a grinding wheel attached thereto, a plate within which said grinding shaft is rotatably mounted, means for angularly positioning said plate for providing grinding of various sized openings during rotary movement of said plate about said shaft, said means including a casing in which said pulleys. are mounted, said plate being pivoted to said casing, means for locking said plate at predetermined selected positions, including an arcuate slot in said plate, a stud threadably engaged with said casing passing through said arcuate slot, a traverse screw, a traverse nut threadably engaged with said screw and engaging said plate whereby rotation of said screw will adjustably move said plate,

said casing being adapted to rotate about said vertically positioned shaft to provide an annular path of rotation of said grinding wheel, according to the frictional effect of bearings journalling said shafts, and according to the resistance imparted by said grinding wheel on a wori piece opening, means for controlling the rotational speed of said casing including a ring gear attached to said casing, a governing member including a train of meshed gears, one gear of which engages said ring gear, a further end gear of which includes a governing shaft attachcl thereto, governing arms attached to said governing shaft, a governor casing attached to said governing member, friction pads attached to said governing arms.

2. A grinding unit comprising a shaft for attachment to a rotary power source, a pulley attached to said shaft, a second smaller pulley driven by said pulley, a further shaft attached to said second pulley, a carriage within which said further shaft is journalled, a third larger pulley attached to said further shaft, a fourth smaller pulley driven by said third pulley, a grinding shaft attached to said fourth pulley including a grinding wheel attached thereto, a plate within which said grinding shaft is rotatably mounted, means for angularly positioning said plate for providing grinding of various sized openings during rotary movement of said plate about said shaft, said means including a casing in which said pulleys are mounted, said plate being pivoted to said casing, means for locking said plate at predetermined selected positions, including an arcuate slot in said plate, a stud threadably engaged with said casing passing through said arcuate slot, a traverse screw, a traverse nut threadably engaged with said screw and engaging said plate whereby rotation of said screw will adjustably move said plate, said casing being adapted to rotate about said vertically positioned shaft to provide an annular path of rotation of said grinding wheel, according to the frictional effect of bearings journalling said shafts, and according to the resistance imparted by said grinding wheel on a Work piece opening, means for controlling the rotational speed of said casing including a ring gear attached to said casing, a governing member including a train of meshed gears, one gear of which engages said ring gear, a further end gear of which includes a governing shaft attached thereto, governing arms attached to said governing shaft, a governor casing attached to said governing member, fricticn pads attached to said governing arms, means for controlling the rotative speed of said casing corresponding to the torque applied through said gear train and said governing arms, including a spring, said governing arms having extending lips against which said spring bears, a cap threadably engaged with said governor casing adapted to bear against said spring to correspondingly regulate the speed of rotation of said governing shaft, such speed of rotation being limited by the contact of said pads with said governor casing.

3. A grinding unit comprising a shaft for attachment to a rotary power source, a casing in which said shaft is journalled, a grinding shaft journalled in said casing including a grinding wheel attached thereto, a mechanism in said casing adapted to translate power to said grinding shaft, means for eccentrically positioning said grinding shaft in said casing for providing grinding of various sized diameters during rotary movement of said casing about said shaft attached to rotary power source, said casing being adapted to rotate about said shaft to provide an annular path of rotation of said grinding wheel, according to friction applied between said shafts and said casing, and according to the resistance imparted by said grinding wheel on a work piece opening, means for controlling the rotational speed of said casing, in relation to said Work piece opening including a governor, said governor being journalled on said casing, a reaction arm attached to said governor and adapted to bear against a fixed abutment.

References Cited in the file of this patent UNITED STATES PATENTS 437,157 Honeyman Sept. 23, 1890 1,306,720 Robinson June 17, 1919 1,730,551 Yerk Oct. 8, 1929 2,347,489 Laxer Apr. 25, 1944 2,364,328 Thorsberg Dec. 5, 1944 2,482,620 Huck Sept. 20, 1949 2,491,940 Tree Dec. 20, 1949 2,546,490 Baldwin Mar. 27, 1951 2,552,663 Bech May 15, 1951 2,641,970 Plimmer June 16, 1953 FOREIGN PATENTS 17,644 Germany Apr. 3, 1882 207,298 Great Britain Nov. 29, 1923 258,427 Germany Apr. 10, 1913 635,952 France Jan. 3, 1928 

